this question has me stumped. Any help would be greatly appreciated.
It goes like this:
For the domain of all sets, give a first-order logic formula saying - There exists no set such that all other sets are its element.
So far I have this:
Let $x$ and $y$ be all sets. $\lnot\exists x\,\forall\,y\,(y\in x \impliedby x\ne y)$
Note, the reason I've put $x$ does not equal $y$ is because the question says "all OTHER" sets, so I interpreted that as, it does not include itself, so it's not a member of itself but again I'm not sure.
The statement:
"There does not exists a set such that all other sets are its elements."
can be written in first order language of set theory $\mathcal{L} = \{\in\}$ as
$\neg(\exists x)((\forall y)(y \neq x \Rightarrow y \in x) \wedge (x \notin x))$